DESIGNER’S HANDBOOK 4189350049C EN
Page 82 of 206
5.7.3.4 RPM pickup cable recommendation
The galvanic separated inputs are well protected and not very sensitive to electrical noise. It is, however,
recommended to use a shielded twisted pair cable in installations where long cables are used or where strong
electromagnetic disturbance may occur. The shield must only be terminated in one end to a good ground
connection and must not be connected to any of the terminals on the XDi.
Tested cable type and length:
The DX1 system test includes a test of both Balluff sensor types connected to the DX1 input using 110 meter
shielded twisted pair cable type Belden 9841NH. This test was performed using a rotating disc with an input
frequency up to 1400 Hz. (The max available frequency from test machine).
The measurements on input signals and the data presentation on the XDi indicated no problem with this cable
length.
The maximum cable length depends on the cable type and the maximum operating frequency, but the conclusion
of the test was that 110 meter @ 1400 Hz was not even close to the maximum cable length.
5.7.3.5 Sharing RPM data from DX1 via CAN
The RPM data calculated based on the pickup signal(s) can be shared on CANopen/XDi-net.
Therefore, it is only necessary to connect the RPM pickup to the first XDi in the indicator system. The rest of the
XDi units will receive their RPM data via CAN; the easiest way is just to use the XDi-net format, but as for analogue
data, the XDi can be configured to send TPDO or RPDO instead or in addition to XDi-net format.
Even XL CAN indicators may be integrated in such a system. It only requires that the XDi unit that is sharing data is
configured to support the XL sCAN data format (TPDO type data).
5.7.3.6 Bidirectional RPM pickup system
To measure bidirectional RPM rotation, it is necessary to configure the virtual indicator to use an RPM input pair.
This is defined in the VS profile.
To be able to determine the direction of the
rotation, the two pickup sensors must be mounted
with a mechanical offset.
The optimal position of the pickup sensors is as
illustrated in the drawing.
Sensor no.1 is right at the centre of a cut-out.
Sensor no. 2 is located with a 25 % offset.
For practical reasons, the two sensors are not
located around the same cut-out; this has no
influence on the function as long as the offset is
correct.
